1. Technical Field
The present invention relates to a liquid discharge device, and a discharge abnormality testing method.
2. Related Art
From the past, inkjet printers as liquid discharge devices for which liquid (ink) is discharged as droplets from nozzles of a head (inkjet head) using the inkjet method to perform image formation on media have become widely popular since it is easy to obtain a high quality printed object at a relatively low cost. The inkjet printer head has a piezoelectric element for vibrating a vibrating plate, a pressure chamber for which liquid is stored in the interior, for increasing and decreasing the internal pressure using vibration of the vibration plate, and a plurality of nozzles provided in communication with the pressure chamber on the head nozzle surface, and liquid is discharged from the nozzles by the piezoelectric element being driven by drive signals to increase and decrease the pressure of the pressure chamber.
In recent years, there has been even further increase in demand for the quality of formed images, and along with that, an even larger number of nozzles are being provided on the nozzle surface of the inkjet printer head. With this kind of head, due to reasons such as an increase in ink viscosity, mixing in of air bubbles, adhesion of dust, paper powder or the like, there are cases when among the large number of nozzles, several nozzles become clogged, and it is not possible to discharge ink droplets. When nozzles become clogged, missing dots occur within the printed image, which is a cause of image quality degradation.
As a method of detecting liquid discharge abnormalities to prevent image quality degradation of images such as of missing dots or the like, for example in Japanese Unexamined Patent Publication No. 2007-30343, introduced is a method whereby drive signals are output to a piezoelectric element, the residual vibration after changes in pressure within the pressure chamber due to those drive signals are detected as changes in the electromotive force of the piezoelectric element, and based on the vibration pattern of that residual vibration, abnormalities are detected in the discharge of ink from the nozzle. Using this discharge abnormality detection method, the presence or absence of discharge abnormalities is confirmed, and when a discharge abnormality is detected, by performing maintenance processing such as nozzle surface sweeping, cleaning or the like, it is possible to prevent image quality degradation.